1. Field of the Invention
The present invention relates to a hydraulic pressure control valve comprising a valve body having a slide bore with a circular cross-section, an inlet port opened in an inner surface of the slide bore, a control pressure port and an outlet port at axially spaced-apart distances in this sequence; a valve spool axially slidably fitted in the valve body; and a first variable orifice and a second variable orifice both formed between the valve body and the valve spool, the first variable orifice controlling the degree of communication between the inlet port and the control pressure port, and the second variable orifice controlling the degree of communication between the control pressure port and the outlet port.
2. Description of the Prior Art
Such a valve having two variables orifices formed between a valve body and a valve spool is known, for example, from Japanese Patent Application Laid-open No. 140129/77.
In the above prior art, however, the variable orifice is defined by a notch provided in the valve spool and an annular groove provided in the inner surface of the slide bore in the valve body. In order to improve the dimensional accuracy of the variable orifice, it is necessary to machine the notch in the valve spool and the annular groove in the inner surface of the slide bore, in each case, with a good accuracy, which is troublesome.